The proposed research is an investigation of vestibular function and the influence of the vestibular system on sensory processing in the brain stem in autistic children. Research from such diverse fields as investigations of disorientation of flight personnel, motion sickness, psychosis, and sleep physiology has led to a reappraisal of the functions of the vestibular system. In the light of these studies, the vestibular system would seem to play a role not only in respect to the control of posture and balance but also in relation to the processing and interpretation of sensory information from the environment while making the proper adjustments for the effect of the individual's own motility on these perceptions. In the proposed level of the central nervous system, and the influence of vestibular stimulation on brain stem auditory evoked responses will be quantified in autistic and normal children. As it is now possible to safely record auditory evoked responses generated in the brain stem from the scalp without discomfort to the subject, the differential effect of concomitant vestibular stimulation on auditory responses at this level of brain functioning will be quantified. The possible effects of the vestibular stimulation on the auditory evoked responses will be studied in relation to the amount of oculomotor activity (nystagmus) induced by the vestibular stimulation. In this way an approach to the study of vestibular influences on the regulation or modulation of sensorimotor interaction in autistic children will be initiated. These neurophysiologic parameters will be correlated with quantified clinical assessments of the severity of the autistic behavior, and with the presence or absence of other associated clinical conditions.